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Chapter 2: Working with Numbers Learning Objectives: 1.To Be Able to Calculate and Use Descriptive Statistics 2.To Be Able to Compare Different Types of Data Using Statistical Inference and Hypothesis Testing 3.To Be Able to Present Data Effectively and Efficiently in Visual Form

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Measures of Spread Range – Difference between Maximum and Minimum Value Standard Deviation – Average Distance of a Given Data Point to the Mean

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Working with Samples Samples are Inherently More Variable than Populations Impossible to Know the “Truth” about Current and/or Future Population Data – Create an Interval that We Can Say with Some Level of Confidence Contains the True Population Mean Formula for Constructing a Confidence Interval: Mean = +/ * Standard Error, Where Standard Error = Standard Deviation/√n

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Working with Bivariate Data Hypothesis Testing Null Hypothesis: The Hypothesis of No Association or Difference Alternative Hypothesis: The Converse of the Null Hypothesis; i.e., There Is Some Association or Difference - When the Direction of the Difference Doesn’t Matter  A Two-Tailed Test. If Direction Does matter, the Test Is One-Tailed Test

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More on Hypothesis Testing Can Never Be Certain What Relationship Truly IS Between Two Variables So, We Use Hypothesis Testing and Statistics to Make Probabilistic Inferences about Relationships